JP2003187950A - Single-turn induction heating coil - Google Patents

Abstract

(57) [Abstract] [Problem] Even if the effective heating length is lengthened to suppress the heating rate, equipment costs can be reduced, and coil maintenance and inspection is easy.
A single-turn induction heating coil capable of heating a steel strip to a Curie point or higher is provided. SOLUTION: A metal strip, and a first surface on the front side extending in the width direction of the metal strip with a predetermined distance from the front and back surfaces of the metal strip and having both ends located outside both ends of the metal strip. And the second conductor portion on the back side and the first conductor portion and the second conductor portion extending in the thickness direction of the metal strip outside the widthwise end of the metal strip. Third end connecting each end of
A single-turn type induction heating coil comprising: a first conductor portion and a second conductor portion each having 1
A fourth conductor section extending two (3 or more) first conductor sections and two (3 or more) open ends of the first conductor section and the second conductor section in the longitudinal direction of the metal strip. A single-turn type induction heating coil, wherein the first and second conductors are connected at positions shifted from each other in the longitudinal direction of the metal strip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil for induction heating of a metal strip, and more particularly to a single turn coil.

[0002]

2. Description of the Related Art Induction heating is a method in which a coil connected to an AC power source is arranged around an object to be heated and an object is heated by Joule heat of an eddy current induced by an alternating magnetic field. Two types of induction heating are available: a transverse method in which an alternating magnetic field intersects the object to be heated perpendicularly, and a solenoid method in which the object is heated by a coil and the alternating magnetic field is applied in parallel to the object. And is selected according to the purpose. In the case of heating the metal strip, the solenoid method is suitable because uniform heating in the width direction is required. Further, the solenoid system includes a multi-turn system in which a coil is wound a plurality of times and a single-turn system in which a coil is wound only once for one power source.

FIG. 10 is a diagram showing an induction heating apparatus for a metal strip using a solenoid type single turn coil disclosed in Japanese Patent Application Laid-Open No. 8-8051 and Japanese Patent Application Laid-Open No. 7-252628. This induction heating device has a front surface conductor and a back surface 3 of the metal strip 1 which are spaced apart from each other by a predetermined distance and which extend in the width direction of the metal strip 1 and whose both ends are located outside the width direction of the metal strip. Part 4 and the conductor part 5 on the back surface side, and one ends of the conductor part 4 on the front surface side and the conductor part 5 on the back surface side, the plate of the metal strip plate 1 outside one end in the width direction of the metal strip plate 1. A single-turn type induction heating coil 7 connected by a conductor portion 6 extending in the thickness direction, an AC power supply device S for applying AC to the other ends of the conductor portion 4 on the front surface side and the conductor portion 5 on the rear surface side of the coil 7. Is equipped with. However, in this conventional technique, in order to suppress the heating rate in order to prevent the deterioration of the steel sheet shape after heating, a plurality of single-turn type induction heating coils are provided in the traveling direction of the metal strip in order to increase the effective heating length. When arranging and arranging the induction heating furnace of a metal strip, the power supply device corresponding to the number of coils is needed, and there existed a problem that equipment cost became expensive.

Further, in this conventional single-turn type induction heating coil, when viewed from the cross-sectional direction of the metal strip, the coil ends outside the both end surfaces of the metal strip are closed, so that the coil is connected to the power source of the metal strip. It was difficult to maintain and inspect the coil because it could not be taken out from the transfer line. Further, in the conventional induction heating device using a solenoid type single-turn coil, when the metal strip 1 is, for example, a magnetic steel strip, it is difficult to heat the Curie point (about 750 ° C.) or higher, and 650 ° C. There is a problem that it can be applied only to heating in the following low temperature region. Furthermore, when the metal strip 1 is a non-magnetic material such as aluminum or SUS, it is difficult to heat the strip itself. The reason why it is difficult to heat above the Curie point of the magnetic strip is that when the temperature near the Curie point increases, the current penetration depth of the eddy current increases and the front and back of the eddy current that goes around the surface layer of the cross section in the width direction. This is because the cancellation occurs and the eddy current stops flowing. Further, it is difficult to heat the non-magnetic strip itself because the eddy current has a large current penetration depth from the room temperature level, and the front and back of the eddy current that surrounds the surface layer of the cross section in the plate width direction cancels each other. This is because eddy currents do not flow.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the problems of the prior art as described above, and even if the effective heating length is increased to suppress the heating rate, the equipment cost can be reduced and the maintenance and maintenance of the coil can be achieved. An object of the present invention is to provide a single-turn type induction heating coil that can be easily inspected and can heat a steel strip to a Curie point or higher.

[0006]

The gist of the present invention is the following contents as described in the claims. (1) A metal strip and a first surface-side surface that is spaced apart from the front and back surfaces of the metal strip by a predetermined distance and extends in the width direction of the metal strip so that both ends are located outside both ends of the metal strip. The first conductor portion and the second conductor portion on the back surface side, and the first conductor portion and the second conductor portion that extend in the plate thickness direction of the metal strip plate outside the widthwise ends of the metal strip plate. A single-turn type induction heating coil including a third conductor portion connecting each end of the conductor portion, wherein one each of the first conductor portion and the second conductor portion is added and two coils are added. The open ends of the first conductor portion and the second conductor portion of are connected by a fourth conductor portion extending in the longitudinal direction of the metal strip, and the first conductor portion and the second conductor portion are connected. Are installed at positions shifted from each other in the longitudinal direction of the metal strip plate. Le.

(2) A surface of the metal strip that extends in the width direction of the metal strip and has both ends located outside both ends of the metal strip with a predetermined distance from the front and back surfaces of the metal strip. The first conductor portion on the side and the second conductor portion on the back surface side, and extending in the plate thickness direction of the metal strip plate outside the end portion in the width direction of the metal strip plate, A single-turn type induction heating coil comprising: a third conductor part that connects each end of a second conductor part, wherein the first conductor part, the second conductor part, and the length of the metal strip plate. Two or more first conductor portions and two or more second conductor portions are respectively provided in parallel to the direction, and three or more first conductor portions and the second conductor portions are provided.
The open ends of the conductor portions are connected by fourth conductor portions that extend in the left-right direction in the longitudinal direction of the metal strip, and the first conductor portion and the second conductor portion are connected to the longitudinal direction of the metal strip. A single-turn type induction heating coil, which is installed at positions mutually shifted in the direction.

(3) The number of expansions of the first conductor portion and the second conductor portion is an odd number of three or more, respectively,
The single-turn induction according to claim 2, wherein the open ends of the even number of four or more even first conductors and the second conductors are connected by the fourth conductors. Heating coil. (4) Covering the outer periphery of the first conductor portion and the second conductor portion excluding the surface facing the front surface and the back surface of the metal strip, with a core made of a material having high magnetic permeability and high resistivity. The single-turn induction heating coil according to any one of (1) to (3). (5) The single-turn type induction heating coil according to (4), wherein the material having high magnetic permeability and high resistivity is ferrite.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail with reference to FIGS. (First Embodiment) FIG.
FIG. 3 is a diagram showing an embodiment in which each of the first and second conductor portions provided on the front surface and the back surface of the metal strip in the present invention has two conductors. The current supplied from the power supply device S is supplied to the power supply device S via the conductors 9, 11, 4, 6, 5, 12, 10. Here, the conductor 9 and the conductor 4 correspond to the first conductor portion of the present invention, and the conductor 5 and the conductor 10 correspond to the second conductor portion of the present invention. Also,
The conductor 6 corresponds to the third conductor portion in the present invention, and the conductor 1
1 and the conductor 12 are equivalent to the 4th conductor part in this invention. Since the first and second conductors are composed of two conductors in this manner, the effective heating length in the longitudinal direction of the metal strip 1 is increased without installing the power supply device S for each coil. It is possible to prevent the deterioration of the shape of the metal strip 1 after heating by suppressing the heating rate. Further, since the coil end portion on one side in the width direction of the metal strip 1 is open, the coil can be carried out together with the power supply to the outside of the transport line of the metal strip 1 for maintenance, inspection, and maintenance of the coil. Is easy.

Further, the conductor 9 and the conductor 4 are replaced by the conductor 10.
It is installed at a position shifted in the longitudinal direction of the metal strip 1 with respect to the conductor 5. As a result, it is possible to prevent the front and back of the eddy currents that go around the surface layer portion of the cross section of the metal strip 1 in the plate width direction from occurring, so that it is possible to heat the steel plate above the Curie point. It can also heat non-magnetic materials. 3 is a cross-sectional view seen from the power supply device S side of FIG. 1, and FIG. 4 is a cross-sectional view seen from the opposite side. It can be seen that the conductors 9 and 4 on the front surface of the metal strip are shifted from the conductors 10 and 5 on the back surface by W in the longitudinal direction of the strip. Further, the conductor 6 corresponding to the third conductor portion has an L-shape, and the shifted conductors 4 and 5 are thereby connected in the plate thickness direction of the metal strip plate.

(Second Embodiment) FIG. 2 shows the first and second parts installed on the front and back surfaces of the metal strip according to the present invention.
It is a figure which shows the embodiment which made each conductor part three conductors. The current supplied from the power supply S is the conductor 14,
The power supply device S is energized via 11, 9, 11, 4, 6, 5, 12, 10, 12, 15. Here, conductor 14 and conductor 9
And the conductor 4 corresponds to the first conductor portion in the present invention,
The conductor 5, the conductor 10, and the conductor 15 are the second in the present invention.
Corresponds to the conductor part of. The conductor 6 corresponds to the third conductor portion of the present invention, and the conductors 11 and 12 correspond to the fourth conductor portion of the present invention. In this way, the first and second conductor portions are composed of three conductors, so that the effective heating length in the longitudinal direction of the metal strip 1 can be increased without installing the power supply device S for each coil. It is possible to prevent the deterioration of the shape of the metal strip 1 after heating by suppressing the heating rate.

Further, the conductor 14, the conductor 9 and the conductor 4
Are arranged at positions shifted in the longitudinal direction of the metal strip 1 with respect to the conductors 15, 10 and 5. As a result, it is possible to prevent the front and back of the eddy currents that go around the surface layer portion of the cross section of the metal strip 1 in the plate width direction from occurring, so that it is possible to heat the steel plate above the Curie point. It can also heat non-magnetic materials. FIG. 5 is a cross-sectional view seen from the power supply device S side of FIG.
Is a sectional view seen from the opposite side. Conductor 1 on the surface of a metal strip
4, conductor 9 and conductor 4 are conductor 15, conductor 10 on the back surface.
Further, it can be seen that the state is shifted by W in the figure in the longitudinal direction of the strip with respect to the conductor 5. Further, the conductor 6 corresponding to the third conductor portion has an L-shape, and the shifted conductors 4 and 5 are thereby connected in the plate thickness direction of the metal strip plate.

(Third Embodiment) FIG. 7 shows the first and second installations on the front and back surfaces of the metal strip according to the present invention.
It is a figure which shows the embodiment which each made the conductor part into four conductors. The current supplied from the power supply S is the conductor 17,
11,14,11,9,11,4,6,5,12,10,12,1
The power supply device S is energized via 5, 12, and 18. Here, the conductor 17, the conductor 14, the conductor 9, and the conductor 4 correspond to the first conductor portion in the present invention, and the conductor 5, the conductor 10, and the conductor 1 are included.
5 and the conductor 18 are equivalent to the 2nd conductor part in this invention.

The conductor 6 corresponds to the third conductor portion of the present invention, and the conductors 11 and 12 correspond to the fourth conductor portion of the present invention. Thus, the first and second
Since the conductor of is composed of four conductors,
The effective heating length in the longitudinal direction of the metal strip 1 can be increased without installing the power supply device S for each coil, and the heating rate is suppressed to prevent deterioration of the shape of the metal strip 1 after heating. can do. Further, since the coil end portion on one side in the width direction of the metal strip 1 is open, the coil can be carried out together with the power supply to the outside of the transport line of the metal strip 1 for maintenance, inspection, and maintenance of the coil. Is easy. The effect is that the first and second conductor parts are
The same effect can be obtained when an even number of conductors, which is equal to or more than one, is used. Furthermore, the conductor 17, the conductor 14, the conductor 9, and the conductor 4
Are installed at positions shifted in the longitudinal direction of the metal strip 1 with respect to the conductor 18, the conductor 15, the conductor 10, and the conductor 5. As a result, it is possible to prevent the front and back of the eddy currents that go around the surface layer portion of the cross section of the metal strip 1 in the plate width direction from occurring, so that it is possible to heat the steel plate above the Curie point. It can also heat non-magnetic materials.

FIG. 8 is a sectional view as seen from the power supply device S side in FIG. 7, and FIG. 9 is a sectional view as seen from the opposite side. It can be seen that the conductor 17, the conductor 14, the conductor 9, and the conductor 4 on the surface of the metal strip are shifted from the conductor 18, the conductor 15, the conductor 10 and the conductor 5 in the longitudinal direction of the strip by W in the figure. . Further, the conductor 6 corresponding to the third conductor portion has an L-shape, and the shifted conductors 4 and 5 are thereby connected in the plate thickness direction of the metal strip plate. The heating conductor common to the first to third embodiments is preferably the following embodiment. The heating conductor is preferably a hollow water-cooled copper pipe having a quadrangular cross section in view of its low electrical resistance and availability.

Further, in order to concentrate the magnetic field (increase the magnetic flux density) and improve the heating efficiency, the conductors 4, 5, 9, 10, 14, 15, 17, 17 on the front surface side and the back surface side of the metal strip plate.
It is preferable that the outer peripheral surfaces 3 of the metal strip plate 1 of No. 8 other than the opposing surfaces of the front surface 2 and the rear surface 3 are directly coated with the ferrite core 21 having a high relative magnetic permeability of 2500 and a high resistivity. According to the single-turn coil configured as described above, the alternating current power supply S can reduce the magnetic circuit resistance at the alternating time generated by the alternating current power supply by the ferrite core 21, increase the magnetic flux density, and increase the magnetic flux density. The eddy current generated in 1 can be increased. Therefore, the time (heating time) required to heat the metal strip 1 to a predetermined temperature can be shortened. Further, although the alternating magnetic field passes through the core made of ferrite, since ferrite is also a high resistivity material, eddy current is not formed and the core temperature does not rise. Further, since ferrite is a high-resistivity material, it is not necessary to provide an electrically insulating layer when coating the core with the coil, and the core can be coated in intimate contact. It is preferable that the radiant heat from the induction-heated metal strip 1 to the core is also satisfactorily transferred and removed by the hollow water-cooled coil structure provided to prevent coil damage. This eliminates the need for a special cooling mechanism for preventing core damage.

[0017]

EXAMPLES Examples in which the present invention is used for heating a steel strip will be described in detail below. A single-turn coil having a coil conductor width W = 6 mm, a core width h = 3.5 mm, and an inter-coil gap G = 6 mm shown in FIG. 1 was used to continuously heat a steel strip at room temperature. The steel strip used is 70 m wide
m, plate thickness t = 0.23 mm, plate passing speed V = 20
The plate was passed at 0 mm / s. Regarding the power supply frequency f, the steel strip was continuously heated at 200 KHz, which is the highest frequency in practical use. At that time, immediately after heating (position in FIG. 3)
a) Width center part, outermost edge, 1 from edge
The temperature of 0 mm part was measured. The results are shown in Table 1. The Curie temperature of the steel strip is 750 ° C. For comparison, using a conventional single-turn coil, a single-turn coil with a coil conductor width W = 6 mm, a core width h = 3.5 mm, and an inter-coil gap G = 6 mm was used, and steel was used under the same conditions as above. The belt is continuously heated and immediately after heating (Fig. 3
The results of measuring the temperature at position a) are shown in Table 1.

[0018]

[Table 1] From Table 1, it can be seen that the single-turn coil of the present invention can uniformly heat the steel strip in the width direction to the Curie point or higher. On the other hand, the heating temperature of Comparative Example 1 is lower than the Curie temperature. Next, the SUS band was continuously heated under the same conditions as described above, and the temperature immediately after heating (position a in FIG. 3) was measured. The results are shown in Table 2.

[0019]

[Table 2] From Table 2, it can be seen that the single-turn coil of the present invention can heat a nonmagnetic metal strip such as a SUS strip uniformly in the width direction. On the other hand, Comparative Example 2 could not be heated at all.

[0020]

According to the present invention, even if the effective heating length is increased to suppress the heating rate, it is not necessary to add a power supply device, so that the facility cost can be reduced and the cross-sectional direction of the metal strip in the plate width direction. Since the conductor is not closed and the one end is opened, it is possible to provide a single-turn induction heating coil in which maintenance and inspection of the coil are easy. Moreover, the steel strip can be heated above the Curie point by shifting the conductors in the longitudinal direction on the front and back surfaces of the metal strip, and a non-magnetic material such as SUS can also be heated.

The present invention has the following effects as compared with the conventional gas heating furnace in which the heating rate is easily suppressed.
The installation space may be about 1/10 of the conventional gas heating furnace. The heating efficiency in the gas heating furnace is about 0.3 in the low temperature range (for example, the steel plate temperature is around 100 ° C.),
In the high temperature range (for example, the steel plate temperature is 800 ° C.), it is 0.
It is about 1. On the other hand, according to the single-turn induction heating coil of the present invention, the heating efficiency is about 0.6 to 0.7 regardless of the heating temperature, so that the heating length can be reduced. Since it has good thermal response, it is easy to operate. For example, in the case of a gas heating furnace, it takes about 30 minutes to change the temperature setting of the gas heating furnace when the type of steel sheet is changed. According to this, it is possible to change the furnace temperature almost immediately after changing the setting only by changing the input power setting.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment in which the first and second conductor portions provided on the front surface and the back surface of a metal strip according to the present invention each have two conductors.

FIG. 2 is a diagram showing an embodiment in which each of the first and second conductor portions provided on the front surface and the back surface of the metal strip according to the present invention has three conductors.

FIG. 3 is a cross-sectional view of the single-turn induction heating coil of the present invention as seen from the power supply device S side of FIG.

4 is a cross-sectional view of the single-turn induction heating coil of the present invention seen from the opposite side of the power supply device S of FIG.

5 is a cross-sectional view of the single-turn induction heating coil of the present invention viewed from the power supply device S side of FIG.

6 is a cross-sectional view of the single-turn induction heating coil of the present invention seen from the opposite side of the power supply device S of FIG.

FIG. 7 is a view showing an embodiment in which each of the first and second conductor portions provided on the front surface and the back surface of the metal strip according to the present invention has four conductors.

8 is a cross-sectional view of the single-turn induction heating coil of the present invention as seen from the power supply device S side of FIG.

9 is a cross-sectional view of the single-turn induction heating coil of the present invention viewed from the opposite side of the power supply device S of FIG.

FIG. 10 is a diagram showing a conventional single-turn induction heating coil.

[Explanation of symbols]

1: Metal strip 2: Strip plate surface 3: Back side of strip 4: Strip plate surface side conductor extending in the width direction of the metal strip plate 5: Conductor on the back side of the strip extending in the width direction of the metal strip 6: Conductor extending in the thickness direction of the metal strip plate 7: Conventional single-turn type induction heating coil 8: Single-turn type induction heating coil of the present invention 9: Strip plate surface side conductor extending in the width direction of the metal strip plate 10: Conductor on the back side of the strip extending in the width direction of the metal strip 11: Conductor extending in the longitudinal direction of the metal strip plate 12: conductor extending in the longitudinal direction of the metal strip 13: Single-turn type induction heating coil of the present invention 14: Strip plate surface side conductor extending in the width direction of the metal strip plate 15: Conductor on the back side of the strip extending in the width direction of the metal strip 16: Single-turn type induction heating coil of the present invention 17: Strip plate surface side conductor extending in the width direction of the metal strip plate 18: Conductor on the back side of the strip extending in the width direction of the metal strip 19: Copper pipe 21: Ferrite core

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ryo Asahiyama             1st Fujimachi, Hirohata-ku, Himeji City Nippon Steel Corporation             Inside the Hirohata Works (72) Inventor Ikuyo Nomura             1st Fujimachi, Hirohata-ku, Himeji City Nippon Steel Corporation             Inside the Hirohata Works F term (reference) 3K059 AA09 AB26 AB28 AD02 AD03                       AD38 AD40 CD52 CD72

Claims (5)

[Claims] 1. A metal strip, and a front surface side having a predetermined distance from the front and back surfaces of the metal strip, extending in the width direction of the metal strip, and having both ends located outside both ends of the metal strip. Of the first conductor portion and the second conductor portion on the back surface side, and extending in the plate thickness direction of the metal strip plate outside the widthwise end portion of the metal strip plate, A single-turn type induction heating coil comprising: a third conductor portion connecting one end of each of the two conductor portions, wherein each of the first conductor portion and the second conductor portion is 1
The number of wires is increased one by one, and the two first conductor parts and the second wires are added.
The open ends of the conductor portions of are connected by a fourth conductor portion extending in the longitudinal direction of the metal strip plate, and the first conductor portion and the second conductor portion are connected to each other in the longitudinal direction of the metal strip plate. A single-turn type induction heating coil that is installed in a shifted position. 2. A metal strip, and a front surface side extending at a predetermined distance from the front and back surfaces of the metal strip, extending in the width direction of the metal strip, and having both ends positioned outside both ends of the metal strip. Of the first conductor portion and the second conductor portion on the back surface side, and extending in the plate thickness direction of the metal strip plate outside the widthwise end portion of the metal strip plate, A single-turn type induction heating coil including a third conductor portion that connects one ends of two conductor portions, the first conductor portion and the second conductor portion, and a longitudinal direction of the metal strip. In parallel with each other, two or more of the first conductor portion and the second conductor portion are respectively added, and three or more of the open ends of the first conductor portion and the second conductor portion are connected to the metal. The first conductor portion and the second conductor portion are connected by a fourth conductor portion that extends alternately left and right in the longitudinal direction of the strip plate. Single-turn induction heating coil, characterized in that installed in serial shifted to each other in the longitudinal direction of the metal strip position. 3. The number of extension of each of the first conductor portion and the second conductor portion is an odd number of 3 or more, and an even number of each of the first conductor portion and the second conductor is 4 or more.
The single-turn induction heating coil according to claim 2, wherein the open ends of the conductor portions of are connected by the fourth conductor portion. 4. The outer periphery of the first conductor portion and the second conductor portion excluding the surface facing the front surface and the back surface of the metal strip is covered with a core made of a material having high magnetic permeability and high resistivity. The single-turn type induction heating coil according to claim 1, wherein 5. The single-turn induction heating coil according to claim 4, wherein the material having a high magnetic permeability and a high resistivity is ferrite.